1. Field of the Invention
The invention relates to quadruped walking platforms that achieve synchronized walking and turning and, more particularly, to quadruped walking platforms that achieve self-phase synchronized walking and turning by using a damper mechanism and a phase lock bar.
2. Description of the Related Art
There are numerous examples in the prior art of walking devices that use a single motor that is coupled to a single crank shaft which in turn drives the two rear limbs that are also connected to two front limbs. The crank shaft typically has two crank throws that have a phase differential of 180 degrees between them with each of the throws rotatably connected to the corresponding rear limb. As a result, the motor causes one side of legs to thrust while the other side is planting, thereby mimicking the walking of a four-legged animal.
These devices can walk in a forward manner when the motor is rotating in that direction. In the alternative, these devices can walk in a reverse direction when the motor is reversed. Although these prior art devices can walk effectively, they are still unsatisfactory for at least two reasons. One problem with these devices is that they lack the ability to alter the phase differential between the left and right sets of limbs. Moreover they may not be able to restore the original phase differential once it has been disturbed. Therefore, these devices lack the ability to turn and to truly mimic the walking motion of a four-legged animal. Likewise, these devices lack the ability to turn on axis. As a result of these deficiencies, these devices cannot avoid obstacles or seek out objects in their environment.
A prior solution for this problem is the use of multiple motors, (e.g., twelve or more motors), that are under servo control from a computer. In these devices, the servo/computer generates the phase and sequence that the motors on the limbs must achieve to walk successfully. This solution can be cost prohibitive because of the need for many motors, a servo, and a computer as well as its inherent complexity. Accordingly, there exists an unfulfilled need for a quadruped apparatus that can turn both conventionally and on axis in a way that is more cost effective than any method taught by the prior art.
A second problem with these prior art devices is that they do not interact with their environment or make other non-ambulatory movements in a manner that resembles animals. Their inability to turn contributes to this problem because they can not interact with their environment because they are unable to alter their course in response to stimuli. In addition, these platforms frequently have only one motor that powers the walking motion of the devices. Therefore, they lack the source of power to create non-ambulatory movements such as moving their head toward a movement taking place around them, rendering them unlike animals. This can be disadvantageous in the robotic and toy fields where the goal is to have a device that is as similar to animals as possible. Accordingly, there exists a further need for a quadruped apparatus that can interact with its environment by turning or making non-ambulatory responses to stimuli.
In accordance with the present invention, a walking apparatus is provided that includes the ability to turn, both conventionally and on axis, and to respond to stimuli in its environment. This is achieved by providing a rapid and effective way to disturb and restore lateral phase differential from the limbs on one side of the apparatus to the other. The result is an apparatus that can turn in a conventional manner when both sets of limbs are moving in the same direction while also being able to turn on axis when both sets of limbs are moving in opposite directions. In addition, the invention provides a means for simple interface and control by a computerized apparatus so that it can process input signals from its environment, choose an appropriate response, and then execute that response. These features render the apparatus more like animals than those devices found in the prior art. Consequently, these apparati can be used in a wide variety of applications ranging from toys to advertising, to robotics, and to remote control devices.
One embodiment of the invention includes a first motor that is attached to the apparatus and is in communication with a first limb. This embodiment also includes a second motor attached to the apparatus that is independent from the first motor. It is in communication with a second limb that is capable of moving at a different rate than the first limb. Next, at least one damper mechanism is interposed between the first limb and the second limb, or other movable components mechanically linked thereto, which typically have a phase differential of 180 degrees between them, such that the damper mechanism will supply force to resist any change in the phase differential between these limbs. This damper mechanism may take the form of a simple torsion spring, but may comprise of other devices that are readily apparent to those skilled in the art such as brakes, clutches, compression springs, piston assemblies, etc. Thus, the phase differential will be maintained unless some force overcomes the force exerted by the damper mechanism.
The apparatus may be powered electrically, chemically, by solar power, etc. to cause the first and second motors to rotate their respective drive shafts. This energy is then mechanically transmitted to the first and second limbs causing them to make a stepping motion. Since the motors and limbs are independent from each other, a regulator may be used in conjunction with these motors so that their speed may be altered with respect to each other, thereby disturbing the phase differential originally established between them by overcoming the force exerted by the damper mechanism. The end result is that one limb will move faster than the other, causing the apparatus to turn in a prescribed radius. Once the force controlled by the regulator is removed from the motor, the force exerted by the damper mechanism will restore the original phase differential until both the first and second limbs are moving at the same rate causing the apparatus to walk in a straight line. Since this embodiment has only two legs, it may also have two wheels so that the apparatus will more closely resemble a quadrupedal animal. As can be seen, this invention provides a more efficient, simple, and cost effective way of providing an apparatus that can turn to seek out an object such as a ball or avoid an obstruction such as a mountain or a chasm than prior art devices.